Yong Kim, Ph.D.UGSI Solutions, Inc.

Vineland, NJ

Impact of Efficient Polymer Activation onImproving Sludge Thickening and Dewatering

MWEA 94th Annual ConferenceBoyne Falls, MI, June 23-26, 2019

Presentation Overview

1. Basics of Polymer• Why polymer activation matters• Viscosity - indicator of polymer solution quality• Effect of dilution water

2. Science of Polymer Activation• Two-stage mixing - dry and emulsion polymers• Residence time - sufficient for polymer uncoiling/dissolution• Two-step dilution - emulsion polymers• Weissenberg effect

3. Case Studies• Neshaminy Water Treatment Plant, PA – emulsion polymer• F. Wayne Hill WRC, Gwinnett County, GA – emulsion polymer• Fairfield-Suisun Sewer District – dry polymer

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Annual Average Dewatering Cost (2011-2014) = $3.7M

K. Tagney and R. Gupta, Reducing Dewatering Costs through Optimization Program, 2017 WEFTEC.

Dewatering Cost at EMWD: $3.7M / yearPolymer Cost: Average $1.2 M / year

Viscosity – Indicator of Polymer Solution Efficiency

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Intrinsic Viscosity of Polymer Solution

Sakaguchi, K.; Nagase, K., Bull. Chem. Soc. Japan, 39, p.88 (1966)

Quantity of friction as measured by the force resisting a flow inwhich parallel layers have at unit speed relative to one another

Polymer supplier data sheet provides a starting pointfor viscosity – critical factor for polymer efficiency

Solenis, Inc.

Effect of Dilution Water Quality

Ionic strength (Hardness): multi-valent ion hinders polymer activation- Soft water helps polymer molecules fully-extend faster- Hardness over 400 ppm may need softener

Oxidizer (chlorine): chlorine attacks/breaks polymer chains- Should be less than 3 ppm- Caution in using reclaimed water for polymer mixing

* Serious negative impact on aging/maturingTemperature*: higher temperature, better polymer activation

- Water below 40 oF may need water heater- Water over 100 oF may damage polymer chains

Suspended Solids/ Turbidity:- In-line strainer recommended- Caution in using reclaimed water for polymer mixing

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*David Oerke, 20% less polymer with warm water, 40% more polymer with 140F sludge, Residuals and Biosolids (2014)

Polymer Activation (Mixing, Dissolution)

(I) Initial Wetting (Inversion)Sticky layer formedHigh-energy mixing -> No fisheyesMost Critical Stage (brief)

(II) DissolutionReptation* or UncoilingLow-energy mixing -> No damage to polymer

Requires longer residence time

Sticky Layer

WaterPolymer (gel)

* de Gennes, P.G., J. Chem. Phys., 55, 572 (1971)

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time

(I) (II)

Oil

(1) Two-Stage Mixing (in mix chamber)higher energy mixing low energy mixing

“Discrete” Two-Stage Mixing -discrete means “separation of highand low energy mixing zones”

One-Stage vs Two-Stage Mixer (Emulsion Polymer)

G-value, mean shear rate (sec-1)

1,700

4,000

1,100

1- stage mixer 2- stage mixer

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DividingBaffle

One-Stage Mixing vs. Two-Stage Mixing

Two-stage mixing significant increase of polymer solution efficiency

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427

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523

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Anionic Polymer Cationic Polymer

Viscosity of Emulsion Polymer Solution, cP

1-stage mixer 2-stage mixer

37% increase

22% increase

(2) Two-Step Dilution - primary mixing (mix chamber)at high conc. (%) then post-dilution to feed

High Concentration at Initial Wetting,Optimum 0.5% wt. = 1.0 ~ 1.5% vol.Need to post-dilute to 0.5% or lower

Inversion of Emulsion: water-in-oil oil-in-water

99.5% Water

70% Polymer gel

30% Oil

Oil

Polymer gel

Polymer 1 gal

Water 100 gal

Neat Polymer > 1.0 % Polymer Solution

Inverting Surfactant

Especially Important for Clarifier at WTP Strip “oil” off the polymer surface- help polymer get exposed to water quickly- break and disperse oil in micron-sized entities

Inverting Surfactant

* AWWA Standard for Polyacrylamide (ANSI-AWWA B453-06), 11, 2006

Two-Step Dilution: Expediting Polymer Activation

Primary MixingPost-Dilution

Primary mixing at “high %” Post-dilution to feed %

Polymer1.0 gph

Polymer1.0 gph

Water400 gph

Water300 gph

Water100 gph

0.25%solution

0.25%solution1.0%

0.25%

Ideal Design

4 x higher content of inverting surfactantto expedite polymer activation

Primary Mixing

Vt = Residence time (t) in flocculating basin: Gt-value

Gt-value = mean shear rate x residence time

Contact time (T) in clear well design: CT calcCT calc = residual chlorine concentration x contact time

Residence time (t) in polymer activationSecond stage of polymer activation – “uncoiling” of long chain polymer moleculesrequires more time under low energy mixing than high energy first stage mixing

(3) Residence Time (in mix chamber)Sufficient residence time of low-energy mixing zone is

required for complete polymer dissolution

Residence Time of Low Energy Mixing Zone

Low energy mixing stage requires“longer” residence time than initialhigh energy mixing stage

Effect of Residence Time in Mix Chamber

Volume of low-energy zone: VLVL,MM = 3* VL,M

M,

0.5

gal

MM

,1.

0 ga

l

370

1795

397

1936

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2500

Cationic Anionic

Effect of Residence Time in Mix Chamber(0.5% polymer solution viscosity, cP)

M MM

• Located Northeast Philadelphia• Operating capacity: 16 MGD• Population served: 40,000• Emulsion polymer use for dewatering alum-carbon

sludge with two 2-M belt filter presses (K-S)

Case Study: Emulsion Polymer SystemNeshaminy Water Treatment Plant, PA

Existing Polymer SystemSiemens M1200-D10AA (2011)

New Polymer SystemUGSI MM1200-D10AA (2016)

Performance Comparison of Two Mix ChambersPraestol A3040L, HMW Anionic Emulsion Polymer

• Side-by-Side Trial from Feb to May 2016• Polymer savings ~ 30%• Sludge throughput increased by 10%• Cake solids improved marginally from 22% to 23%

Impact of Residence Time of Low-Energy Mix ZoneNeshaminy Water Treatment Plant, PA

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

2/9/16 2/16/16 2/23/16 3/1/16 3/8/16 3/15/16 3/22/16 3/29/16 4/5/16 4/12/16 4/19/16 4/26/16 5/3/16 5/10/16 5/17/16

Poly

mer

Usa

ge, l

b/to

n

Test Date

Polymer Usage of Two PolyBlend Systems

M1200

MM1200

MM

, 1.

0 ga

lM

, 0.

5 ga

l

• Design capacity: 60 MGD• Annual cost of polymer is significant ($1.2 million)

• Thickening ~ $400,000 (RDT)• Dewatering ~ $800,000 (Centrifuge)

• SNF/Polydyne Clarifloc SE-873, crosslinked

Case Study: Emulsion Polymer SystemF. Wayne Hill WRC, Gwinnett County, GA

Courtesy by Jacobs Engineering and Gwinnett County

Three Polymer Systems for Pilot TrialsOptimum feed concentration: 0.5% to 0.7%

UGSI MM2400-P30AB(2400 gph/30 gph)Two-stage mixing

Mechanical, 3450 rpm

FloQuip EA70P(4200 gph/30 gph)Single-stage mixing

Hydraulic

ProMix L6000-30P(6000gph /30 gph)Three-stage mixing

Mechanical, 1725 rpm

Courtesy by Jacobs Engineering and Gwinnett County

Trial results demonstrate that UGSI two-stage mixingprovides significant polymer savings vs. FloQuip

(25% with UGSI, 10% with ProMinent)

Test Polymer BlendingUnit & Centrifuge

AveragePolymer

Dose(lbact/dT)

CentrifugeSludge FeedFlow Range

(gpm)

Average DryCake Solids,

TS (%)

AverageCentrate TSS

(mg/L)

Average PercentCapture

(%)

Pilot 1

UGSI Polyblend®Centrifuge #10 25.7 (± 4.2) 100 - 180 20.4 (± 1.7) 184.4 (± 48.4) 99.5 (± 0.1)

SNF FloQuipCentrifuge #5 33.9 (± 4.1) 100 - 200 21.5 (± 0.8) 193.5 (± 34.5) 99.5 (± 0.1)

Pilot 2

ProMinent ProMix®Centrifuge #10 28.0 (± 3.2) 100 - 180 20.1 (± 1.8) 190.6 (± 41.4) 99.5 (± 0.1)

SNF FloQuipCentrifuge #5 31.3 (± 1.8) 100 - 200 21.7 (± 1.5) 183.0 (± 20.2) 99.5 (± 0.1)

Courtesy by Jacobs Engineering and Gwinnett County

First StageHigh Energy Mixing

(3,450 rpm, < 0.5 sec)

Second StageLow Energy Mixing

(60 rpm, 20 min)

DD4 Disperser Mix and Hold Tanks

PolyBlend® Dry Polymer SystemTwo-Stage Mixing

Polymer SolutionStorage/Holding

(no mixing)

First-Stage of Dry Polymer Mixing:High Energy Initial Wetting

Very High-Energy Mixing for Short Time

G = 15,000 sec-1

3,450 rpm for < 0.5 sec

Disperses Individual Polymer Particles

* No Fisheye Formation

* Shorter Mixing Time in Next Stage

Water inSolution Out

Mixing Tank for Dissolution of Dry Polymer

Patented Hollow-Wing Impeller

No Weissenberg Effect

Large Impeller, 70% of tank diameter

Uniform Mixing Energy

Low RPM, 60 rpm

Low-intensity Mixing

Minimize Damage to Polymer Chain

Shorter Mixing Time – Due to high energy DD4

20 - 30 min for Cationic Polymer

30 - 40 min for Anionic Polymer

Short mixing time minimizes damage

to polymer chain

Weissenberg Effect (undesired) in Polymer Mixing

Water(Newtonian)

Polymer Solution(Non-Newtonian, Pseudoplastic)

extremely low mixing

very high mixing

extremely low mixing

* Polymer solution exceeding “critical concentration” climbs up mixing shaft* Extremely non-uniform mixing* Critical factor for “conventional” polymer mix tankmax 0.2% limit for HMW polymer

Notice polymer solution is “climbing” up the mixer shaft(30 min after mixing (Nalco TX13182): 0.25%, 0.50%)

Polymer Mixing Tank With No Weissenberg Effect

Impeller / tank diameter > 0.7 Cationic Polymer Solution @ 0.75%

Eye of impeller

Hollow-wing impeller

PVC sleeve aroundmixer shaftseparates polymersolution fromrotating shaft

PVC sleeve preventsWeissenburg effect at highconcentration, up to 1.0%

Why high conc. solution?* Smaller tank size* Longer shelf life solution

Rotating shaft

• Solano County, CA, 40 miles North San Francisco• Design capacity: 24 MGD tertiary treatment/ UV• Population served: 135,000• Polymer use for dewatering (screw press) and thickening

(GBT)

Problems with existing polymer system• Struggled to make proper polymer solution• Polymer performance inconsistent• Frequent maintenance issues

FKC screw press runs at average 70 gpm of sludge(2% solids content)

Case Study: Dry Polymer Mixing SystemFairfield-Suisun Sewer District, CA

Pilot Testing with Two Polymer Mix Equipment

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Existing Polymer System• Initial wetting: air blower –> wetting head• Mixing: two (2) 4,600 gal mix/age tanks• 1 hour mixing and 4 - 8 hour aging time

UGSI PolyBlend Dry Polymer Demo System• Initial wetting: high-energy mechanical mixing• Mixing: two (2) 360 gal mix tanks• 20 minute mixing, 10+ minute transfer time

Newly Installed FSSD Polymer System

Hollow wing impellerExisting impeller

Old: Two 4,600 gal mixing/aging tanks* 60 min mixing, 2-4 hour aging

New: Two 1,000 gal mixing tanks* 30 min mixing, 15 min holding

FSSD Installed New PolyBlend®DP2000Performance Data in 2016

38.3 38.435.2 34.5

19.6

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2012 2013 2014 2015 2016

FSSD saved 42% on Screw Press Polymer in 2016despite an increase in solids throughput by 18%

Slud

ge P

roce

ssed

, DT/

year

How to Achieve this Result?initial high-energy mixing is critical

Polymer dissolution time, ts ~ (diameter)2 Tanaka (1979)*

d

10*d

Assume ts 1 min

ts 100 min

Initial high-energy mixing (DD4) No fisheye formationSignificantly shorter mixing time Less damage to polymer structureBetter quality polymer solution Less Polymer Used

* Tanaka, T., Fillmore, D.J., J. Chem. Phys., 70 (3), 1214 (1979)

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• Good quality dilution water will yield to more efficient polymer solution.• Emulsion polymer activation

• Two-stage mixing: very high-energy mixing at initial wetting stage iscritical to prevent fisheye formation, followed by low-energy mixing tominimize damaging polymer chain.

• Sufficient residence time of low-energy mixing stage is required toachieve fully dissolved homogeneous solution.

• Two-step dilution helps proper polymer activation by maximizing thevalue of breaker surfactant.

• Dry polymer activation• Very-high energy mixing at initial wetting stage is critical.• Low-speed and uniform mixing impeller that prevents Weissenberg

effect should be used at the second stage mixing tank.

Summary

Thank YouAny Questions?YKim@UGSIcorp.com